PI Perspective #46

September 2008     View PDF     En español

Immune based therapy offers intriguing possibility

by Paul Dalton

In part of a small but interesting session focused on immune based therapies, Dr. R. Gandhi of Massachusetts General Hospital presented data comparing two immune based approaches in people interrupting HIV treatment. The study compared injections of dendritic cells (DCs) alone vs. DCs + canarypox (CP) virus in people with undetectable HIV levels while on potent HIV treatment but undergoing a treatment interruption.

Volunteers had special blood cells called monocytes taken from their bodies, which were then treated with a cocktail of chemicals to turn them into DCs. These DCs are a type of antigen presenting cell that plays a key role in the immune response to HIV. The theory was that by adding a CP virus, which in some studies increases the activity of DCs, volunteers might better be able to control HIV replication when interrupting treatment.

In this randomized study, 29 people were assigned to get injections of DCs alone or DCs + CP virus 3 times, over a 15-week period. During their first 2 injections, everyone also received injections of a substance called KLH, to help measure the strength of the immune response. After the last injection everyone stopped their HIV treatment.

Researchers looked for differences in HIV levels after 10–13 weeks off HIV treatment. While overall there were no differences in HIV levels between the two groups, there were some hints that this approach might warrant more study.

Specifically, 4 people in the DC + CP virus group had HIV levels below 5,000 copies/mL after 10–13 weeks, compared to none in the DC only group. However, these differences were not sustained after one year. This short-term difference was intriguing enough to make the investigators consider more research on this approach.

It should be noted that this was a small study, the results which may pan out in larger study. It was also done between 4 and 5 years ago, before the most recent rash of negative studies on treatment interruptions, including SMART. Audience members and Dr. Gandhi discussed the ethics of this kind of study in light of the negative findings from SMART and similar studies.